An Icon Font is a collection of icons packed as a web font which can be later used on website using some rules and css etc. There are so many benefits of using Icon fonts on websites over icons images. Some of best and free icon fonts providers are: IcoMoon, Font Awesome, Social Media Icon, Web Symbols and Zurb Foundation Icons etc. Since these icons are fonts so developer can control its basic attributes such as color, text-shadow, resize and transparency/opacity level.
Free download for Windows and Mac!